Netlogo ERROR - DISTANCE预期输入是一个代理但是得到了数字0而不是

Question

我正在尝试为一种模型创建3种类型主机的家庭范围，该模型旨在根据三种主机类型的存在来模拟横向景观的移动。

使用上一篇文章中描述的一些代码，我创建了以下代码。当我运行模型时，我最终收到以下错误消息：

DISTANCE预期输入为代理，但却改为0。

非常感谢任何有关此问题的帮助。

以-去

  if ((week-id = 13) or (week-id = 25) or (week-id = 33))
  [ask patches
    [sprout-mice 2
      [set color gray
       set shape "mouse side"
       set size 0.5
      setxy random-xcor random-ycor]
    ]
  ]

  if week-id = 17[
    let total-deer count deer
    ask n-of (total-deer / 2) patches
    [sprout-deer 1
      [set color brown
       set shape "deer"
       set size 1
        setxy random-xcor random-ycor]
    ]
   ]

  if week-id = 17[
    let total-raccoons count raccoons
    ask n-of (total-raccoons) patches
    [sprout-raccoons 1
      [set color black
       set shape "wolf 2"
       set size 0.5
       setxy random-xcor random-ycor]
    ]
  ]

  mice-mortality
  ;print (count mice)

  if (week-id = 40)
  [deer-mortality]
  ;print(count deer)

  if (week-id = 45)
  [raccoon-mortality]
  print (count raccoons)


 ask deer
  [deer-move]
 ask raccoons
  [raccoons-move]
 ask mice
  [mice-move]

子模型：

to deer-move
  right random 50
  left random 50
  forward 1
end

to raccoons-move
  ifelse distance home-patch > 10
  [face home-patch]
  [right random 90
    left random 90]
  forward 1
end

to mice-move
  ifelse distance home-patch > 2
  [face home-patch]
  [right random 90
    left random 90]
  forward 1
end